如何在计算机上管理不同的python版本

Question

I recently moved my os from debian7 to archlinux. On debian 7, the default python version is python2.7 but on archlinux the default is python3.4.

I once wrote a spider program using beautifulsoup4 on my debian7 but now I want to run this program on archlinux.

I use sudo pacman -S python-pip to install pip and then use sudo pip install beautifulsoup4 . But this time this package goes into /usr/lib/python3.4/site-packages/ .

I know I can download bs4 to my spider's directory and run it with python2, but I just want to know how do you install packages using pip since you have 2 python version installed. And btw if I change the default python link to python2*, will it break my system?

Answer 1

Try python2-pip and pip2 or pip2.7 .

In arch linux all of the python 3 packages have no version number and all the python 2 packages have a 2 . The commands are the same way.

To select what version a script uses use the version number in the hashbang.

#! /usr/bin/env python2

or

#! /usr/bin/env python3

I'm not sure if debian has a python2 link but they can easily be created on systems where /usr/bin/python is python2.7 .

sudo ln -s /usr/bin/python /usr/bin/python{2,2.7}

Answer 2

"on archlinux the default is python3.4" - wow, this is ambitious.

The archlinux wiki on Python provides a lot of tips. You should install python2-pip to make sure that pip is installed for the right version.

Answer 3

Archlinux usually provides packages prefixed with python- for Python 3.x and python2- for Python 2.x. You can also use virtualenv to manage local Python environments, which means you can have a Python2 project and a Python3 project without conflicts between them.